button-native ionic 4 update a tag css code example
Example: ion button transparent
<ion-button (click)="onClick()" fill="clear">
<ion-icon slot="icon-only" name="home"></ion-icon>
</ion-button>
<ion-button (click)="onClick()" fill="clear">
<ion-icon slot="icon-only" name="home"></ion-icon>
</ion-button>